Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as medical, automobile and other applications. The typical image sensor operates as follows. Image light from an external scene is incident on the image sensor. The image sensor includes a plurality of photosensitive elements such that each photosensitive element absorbs a portion of the incident image light. Each photosensitive element included in the image sensor, such as photodiodes, generates image charges upon absorption of the image light. The amount of generated image charges is proportional to the intensity of the image light. The generated image charges may be used to produce an image representing the external scene.
The device architecture of image sensors has continued to advance at a great pace due to increasing demands for higher resolution, lower power consumption, increased dynamic range, etc. These demands have also encouraged the further miniaturization and integration of image sensors into these devices. For high dynamic range image sensors, combination pixels are usually used to sense individual electromagnetic radiation wavelength in order to accommodate a wide range of lighting situations. For example, in a combination red pixel, one sub-pixel can be used to sense bright red light conditions while another sub-pixel can be used to sense low red light conditions. The miniaturization of image sensors may result in a decreased distance between neighboring photosensitive elements. As the distance between photosensitive elements decreases, the likelihood and magnitude of optical and electrical crosstalk between photosensitive elements may increase.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.